This invention pertains to pre-peeling of veneer block moisturizing, and more particularly, to a novel vault construction useable for such an operation.
In preparing a block for veneer peeling, it is customary to place the block in what is known as a steam vault, wherein it is subjected to steam until it has absorbed a certain amount of moisture and heat, as determined empirically over the years for different kinds of woods. A reason for this is that such an operation improves significantly the quality of veneer, and increases what is known as the overrun recovery yielded from blocks.
Steam or moisturizing vaults in the past have typically taken the form of elongated cavities wherein blocks to be moisturized are placed and subjected to steam and/or heated water. In the past, typical methods of introducing steam and water have included direct injection via overhead nozzles, as well as injection of steam upwardly from floor level. Steam has also been used in at least one other way, namely, via a heat exchanger to create a hot water bath which is sprayed on the blocks in a vault.
Such methods of moisturizing have proved, for many reasons, to be extremely costly, ineconomic, and time-consuming. Apart from the specific prior art manners of steaming or moisturizing, which themselves require huge volumes of heated steam and water, an attendant and significant problem has been the lack of an adequate steam or moisture barrier adjacent the opening to a vault through which access is gained. For example, it is common in prior art vaults simply to have such an opening closed off by a loose flap of a fabric material, such as canvas. Another kind of closure often takes the form of a multi-panel, hinged, "garage-like" overhead door. In other words, not much attention has been paid to the need to avoid significant steam leakage and loss through a vault's opening. While significant steam loss is important to avoid, it is also important that a vault not be so tightly sealed that dangerous pressures build up inside. Thus, it is desirable to produce a moisture seal for a vault opening which both maximizes the containment of steam in the vault, and minimizes the likelihood of a dangerous pressure buildup.
A general object of the present invention is to provide a unique vault construction usable for the purpose above mentioned, which construction takes the above-referred-to concerns into consideration in an extremely practical and satisfactory manner.
More particularly, an object of the invention is to provide a vault having an opening which is exposed and closed off through what might be thought of as a guillotine-like rigid panel, or door, that slides vertically in a pair of upright lateral confronting channels.
Another object of the invention is to provide such a vault wherein the base of its opening is defined by a specially prepared smooth surface, such as a smoothly troweled cement apron, on which the base of the door, with the same closed, rests in close conformity.
A related object is to provide such a vault construction wherein the door is raised and lowered through laterally spaced lift apparatus, each of which accommodates vertical adjustment therein in order to angulate door in such a manner as to assure proper seating on the base apron when the door is closed.
Cooperating with the vault opening structure just briefly mentioned, the apparatus of the invention also features a moisturizing system wherein moisturizing is accomplished through the overhead injection into the vault, of a blend produced by the controlled mixing of steam and cold water. Such an injection technique has been found to prove to be both extremely effective in moisturizing blocks in a vault, and to be notably efficient from an energy and water-consumption standpoint in comparison with prior art moisturizing approaches.
Using vault apparatus constructed as generally outlined above, several significant advantages over prior art apparatus are found to exist. For example, and considering a typical prior art vault of a given size having a charge of Douglas fir blocks, a typical requirement for heated steam calls for a water usage rate of between about 400 and about 600-gallons-per-hour. Further, moisturizing times in the past typically lie in the range of about 8 to about 14-hours. By way of comparison, with a vault of substantially the same size constructed in accordance with the present invention, and holding a like charge of blocks, water-flow requirements are more typically about 7-gallons-per-hour, and total moisturizing times reside in the range of about 4 to 6-hours.
Thus, not only does the apparatus of the invention significantly reduce water resource requirements, and hence heating energy requirements, but also greatly minimizes what is known as the "cooking" time for a charge of blocks.
These and other objects and advantages which are attained by the invention will become more fully apparent as the description which now follows is read in conjunction with the accompanying drawings.